ΔE 17.0, loose: different enough that you should pick on purpose. Deep Blue is a little lighter, more saturated, cooler than Leviathan Purple.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Deep Blue is a little lighter, more saturated, cooler than Leviathan Purple.
The same difference applies the other way round: Leviathan Purple is a little darker, more muted, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Leviathan Purple on the colour wheel See Deep Blue on the colour wheel
All matches: Leviathan Purple equivalents · Deep Blue equivalents